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Macintosh SE refuses to boot ("barcode" like video pattern)

G

giobbi

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Dec 23, 2012
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São Paulo country, Brazil
Hi all,

After one year stored on a shelf, my Macintosh SE surprised me refusing to boot. All I get is this video pattern and some beeps:

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Every ~20 secs. it does a refresh on the upper screen:
attachment.php


I removed, clean e put back again the four RAM cards and I re-seated the three roms. No changes.

I measured the MB caps value (but not the power board ones yet), and they seems to be not too far from the nominal range. I measured without to remove them (except for two caps that gave me a totally wrong value).

Since I have no experience about mac and a very little experience in electronics, I'm here to ask your help...

--Giovi
 

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You could sell it on eBay as known working! It worked when tried it a year ago!

On the serious side, someone who actually knows Macintoshes will have a better answer, but it looks to me like bad RAM.
 
KC9UDX said:
You could sell it on eBay as known working! It worked when tried it a year ago!
Click to expand...

LOL "VERY RARE APPLE ITEM! I haven't a cable so it's sold as is, but it should working!" Buy it Now, 1000 USD :mrgreen:

KC9UDX said:
On the serious side, someone who actually knows Macintoshes will have a better answer, but it looks to me like bad RAM.
Click to expand...

system ram or video ram? maybe system, 'cause if it was a bad video ram should at least appear some chars... ?
I've read most people with bars or checkers pattern found the issue is related with leaking caps. Of course I'm always running on the wild side, unsoldering ICs... :-(

--Giovi
 
Well, I'd check the power supply first, which could be leaky condensers, but since you already checked them, maybe, maybe not. Either way, it could be a power supply issue.

Else, if I had to choose solely between video and system RAM, I'd wager on system RAM, at this point.
 
KC9UDX said:
Well, I'd check the power supply first, which could be leaky condensers, but since you already checked them, maybe, maybe not. Either way, it could be a power supply issue.
Click to expand...

well, caps seems to be ok on the power board too. At least they aren't leaking...

KC9UDX said:
Else, if I had to choose solely between video and system RAM, I'd wager on system RAM, at this point.
Click to expand...
I tried to remove SIMM 3 and 4, running only on 1 and 2, and swapping ram cards. I discovered the mac probably doesn't boot with only two ram banks. Strange, blinking video patterns.

Honestly I don't know what to check now, and how. I'm sure this kind of problem isn't so unusual... maybe somebody here already had it before?

--Giovi
 
giobbi said:
well, caps seems to be ok on the power board too. At least they aren't leaking...
Click to expand...

Leaking or not leaking does not indicate good nor bad electrical function. But if you checked them with a decent capacitance tester (not the time delay kind) and they tested good, they're good.

I tried to remove SIMM 3 and 4, running only on 1 and 2, and swapping ram cards. I discovered the mac probably doesn't boot with only two ram banks. Strange, blinking video patterns.
Click to expand...
Or, it's coincidental, at this point.[/QUOTE]

vwestlife said:
Washing the logic board might fix it...
Click to expand...

I'm inclined to think pulling and reseating the ROMs would have done the same. At the very least, remove all socketed chips prior to washing, anyway. It makes cleanup so much easier!
 
KC9UDX said:
Leaking or not leaking does not indicate good nor bad electrical function. But if you checked them with a decent capacitance tester (not the time delay kind) and they tested good, they're good.
Click to expand...

well, I'm not sure what kind of capacitance meter I have... It's a cheap chinese model: http://www.amazon.com/Honeytek-A6013L-Capacitor-Tester/dp/B0036FQ3FW but it's a pure capacitance meter, so I believe it should do the job.

KC9UDX said:
I'm inclined to think pulling and reseating the ROMs would have done the same. At the very least, remove all socketed chips prior to washing, anyway. It makes cleanup so much easier!
Click to expand...

Well, the second check I usually do when I get a broken board, expecially when it's known to be good and suddenly stopped to work, is to pull out every socketed chip, sand the pins and reseat it back in place, just to be sure it's not a simple problem concerning rust, oxidation, bad contact, etc.
The first check is obviously chasing bad caps. It's unbelievable how many faults can be fixed simply replacing old, popping and/or leaking caps :tellme:

However tomorrow I will try to wash it with warm water and soap, and we'll see...

--Giovi
 
NeXT said:
SE logic boards do not use surface mount capacitors. There are a few axials but otherwise they are immune to that leakage problem. They were really robust machines.

I'd also looking into at least reseating the ROM and RAM. Try switching sticks between slots.
Click to expand...

I already reseat both ROM and RAM and I also tried to switch sticks... no changes :-(
I also extracted the big, square IC from its 4 sides socket... again, no changes.

--Giovi
 
On the Mac SE Service Manual it is written that this is due to a bad logic board or analog board but usually this is due to bad ram.
 
...and, in every case, you were right: you can't fix an SE model simply washing the board, since it's a fix for leaking caps only.

I mean, the board doesn't work yet, even after the bath.

Is there any jumper/setting I can change for to use 1, 2 or 3 RAM banks only, instead of 4 ? Just to understand if the problem is one of the system RAM sticks.

BTW are there other components directly involved with system RAM ? Like 74... ICs, and so on?
 
KC9UDX said:
Based on what I read, that's not "Simasimac", it's "Jail Bar".
Click to expand...

Yes... more or less. The pattern they're talking about is slightly different from mine: http://www.biwa.ne.jp/~shamada/fullmac/repairEng.html#JailBar

More: the site is referred to the Macintosh SE/30, Mine is Macintosh SE. There. He's talking about 8 ram banks, I have just four slots, SIMM1 to SIMM 4. And I haven't SMD caps (and that is good!). And they're talking about a memory upgrade.

I haven't memory sticks to change, so I can't say if it's a bad ram. But... if it was a system ram problem, changing the sticks order on the motherboard, should not to change the behavior or, at least, the bar pattern? I mean, can't be some 74... IC problem, i.e. 74LS245 (just an example)? In this case would be easier to solve...
 
68k said:
There are so many things wrong with this video. This is an example of how NOT to clean a circuit board.
Click to expand...

I wash circuit boards all the time, there's absolutely nothing wrong with doing it IF you properly dry the motherboard afterwards.

Letting it sit to drip-dry isn't a great idea since mineral deposits can build up. You generally want to use a powerful squirrel blower or even better an air compressor to get the water out from under the surface mounted ICs.

This cleaning process is only reserved for the most nasty of motherboards though, like those that have been in a smokers home or in a horrible nasty environment.
 
You always want to remove all socketed ICs and batteries.

It's never a good idea to use detergents or soak a circuit board in a tub of water.

I generally use running distilled water when cleaning circuit boards, then dry immediately and allow to sit under a fan for the remainder of the day.
 
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